Pressure-responsive devices, such as those comprising diaphragms, are well known. However where these pressure-responsive elements are intended to deflect in response to pressure differentials resulting from inhalation of air, then they are often unsatisfactory as they require relatively large pressure differentials for deflection to occur. A person whose inhalation of breath is intended to provide this pressure differential can have difficulty in producing sufficient force to deflect the pressure-responsive element. This is particularly so in asthma inhalers used to dispense doses of medication in response to inhalation by a patient, rather than in response to a manual trigger.
It is an aim of the present invention to provide a pressure-responsive device which is sensitive to small pressure differentials, an inhaler incorporating such a pressure-responsive device and also an associated method of manufacture.
The invention is not intended to be limited to use only in the field of inhalers, but may be applicable in any field requiring a pressure-responsive device sensitive to small pressure differentials.